scholarly journals Biogeochemical Controls on the Redox Evolution of Earth’s Oceans and Atmosphere

Elements ◽  
2020 ◽  
Vol 16 (3) ◽  
pp. 191-196 ◽  
Author(s):  
Christopher T. Reinhard ◽  
Noah J. Planavsky
Keyword(s):  
Redox State ◽  
Modeling Tools ◽  
Evolutionary Trajectory ◽  
Geochemical Tracers ◽  
Atmosphere System ◽  
Ocean Atmosphere ◽  
Dramatic Shift ◽  
Redox Evolution

The redox state of Earth’s atmosphere has undergone a dramatic shift over geologic time from reducing to strongly oxidizing, and this shift has been coupled with changes in ocean redox structure and the size and activity of Earth’s biosphere. Delineating this evolutionary trajectory remains a major problem in Earth system science. Significant insights have emerged through the application of redox-sensitive geochemical systems. Existing and emerging biogeochemical modeling tools are pushing the limits of the quantitative constraints on ocean–atmosphere redox that can be extracted from geochemical tracers. This work is honing our understanding of the central role of Earth’s biosphere in shaping the long-term redox evolution of the ocean–atmosphere system.

scholarly journals Regulatory redox state in tree seeds

2017 ◽  
Vol 86 (4) ◽  
Author(s):  
Ewelina Ratajczak ◽  
Karl Josef Dietz
Keyword(s):  
Redox State ◽  
Redox Status ◽  
Long Term Storage ◽  
Tree Seeds ◽  
Term Storage ◽  
Intermediate Seeds

Peroxiredoxins (Prx) are important regulators of the redox status of tree seeds during maturation and long-term storage. Thioredoxins (Trx) are redox transmitters and thereby regulate Prx activity. Current research is focused on the association of Trx with Prx in tree seeds differing in the tolerance to desiccation. The results will allow for better understanding the regulation of the redox status in orthodox, recalcitrant, and intermediate seeds. The findings will also elucidate the role of the redox status during the loss of viability of sensitive seeds during drying and long-term storage.

Role of upper-most crustal composition in the evolution of the Precambrian ocean–atmosphere system

2018 ◽  
Vol 487 ◽  
pp. 44-53 ◽  
Author(s):  
R.R. Large ◽  
I. Mukherjee ◽  
I. Zhukova ◽  
R. Corkrey ◽  
A. Stepanov ◽  
...  
Keyword(s):  
Crustal Composition ◽  
Atmosphere System ◽  
Ocean Atmosphere

scholarly journals Recycled selenium in hot spot–influenced lavas records ocean-atmosphere oxygenation

2020 ◽  
Vol 6 (39) ◽  
pp. eabb6179
Author(s):  
Aierken Yierpan ◽  
Stephan König ◽  
Jabrane Labidi ◽  
Ronny Schoenberg
Keyword(s):  
Hot Spot ◽  
Atmospheric Oxygen ◽  
Sediment Record ◽  
Atmosphere System ◽  
Ocean Atmosphere ◽  
Selenium Isotope ◽  
Mass Dependent ◽  
Global Surface ◽  
Significant Mass

Oxygenation of Earth’s oceans and atmosphere through time has consequences for subducted surface signatures that are now stored in the mantle. Here, we report significant mass-dependent selenium isotope variations in modern hot spot–influenced oceanic lavas. These variations are correlated with tracers of mantle source enrichment, which can only be explained by incorporation of abyssal pelagic sediments subducted from a redox-stratified mid-Proterozoic ocean. Selenium geochemical signatures of these sediments have mostly been preserved during long-term recycling and may therefore complement the global surface sediment record as ancient oxygen archives. Combined deep mantle and surface perspectives, together with emerging models for atmospheric oxygen based on selenium systematics, further imply a significantly oxygenated ocean-atmosphere system throughout the mid-Proterozoic.

Mid-Proterozoic redox evolution and the possibility of transient oxygenation events

2018 ◽  
Vol 2 (2) ◽  
pp. 235-245 ◽  
Author(s):  
Charles W. Diamond ◽  
Timothy W. Lyons
Keyword(s):  
Energy Requirements ◽  
Long Term Conditions ◽  
Animal Evolution ◽  
Proxy Records ◽  
Large Size ◽  
Ocean Atmosphere ◽  
History Of ◽  
Important Possibility ◽  
Redox Evolution

It is often assumed that rising environmental oxygen concentrations played a significant role in the timing of the first appearance of animals and the trajectory of their early proliferation and diversification. The inherent large size and complexity of animals come with large energy requirements — levels of energy that can best, if not only, be acquired through aerobic respiration. There is also abundant geochemical evidence for an increase in ocean–atmosphere O2 concentrations in temporal proximity with the emergence of the group. To adequately test this hypothesis, however, a thorough understanding of the history of environmental oxygenation in the time between the first appearance of eukaryotes and the eventual appearance of animals is necessary. In this review, we summarize the evidence for the prevailing long-term conditions of the Proterozoic Eon prior to the emergence of Metazoa and go on to highlight multiple independent geochemical proxy records that suggest at least two transient oxygenation events — at ca. 1.4 and ca. 1.1 billion years ago (Ga) — during this time. These emerging datasets open the door to an important possibility: while prevailing conditions during much of this time would likely have presented challenges for early animals, there were intervals when oxygenated conditions were more widespread and could have favored yet undetermined advances in eukaryotic innovation, including critical early steps toward animal evolution.

Abusive head trauma (AHT) outcome at long-term follow-up and the role of elective neurosurgical approach: A report of 22 cases

2013 ◽  
Author(s):  
Francesca Menegazzo ◽  
Melissa Rosa Rizzotto ◽  
Martina Bua ◽  
Luisa Pinello ◽  
Elisabetta Tono ◽  
...  
Keyword(s):  
Head Trauma ◽  
Abusive Head Trauma ◽  
Long Term Follow Up
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